The present invention relates to a vehicle attitude control device.
More specifically, the present invention relates to a device for controlling the attitude of a vehicle equipped with a robot-operated mechanical transmission, to which the following description refers purely by way of example.
As is known, over the past few years, a sharp increase has been recorded in the number of vehicles equipped with robot-operated mechanical transmissions, i.e. a conventional mechanical transmission with a group of electrohydraulic actuators for shifting gear under the supervision of an electronic central control unit, which drives the electrohydraulic actuators controlling the clutch and gear shift control shafts so as to shift gear with no direct intervention on the part of the driver.
The electronic central control unit can operate either fully automatically, i.e. itself deciding independently when and how to shift gear; or manually, i.e. by performing the commands entered directly by the driver, after first determining they are mechanically compatible.
Unfortunately, unlike conventional automatic transmissions with a hydraulic torque converter, robot-operated mechanical transmissions of the above type, when effecting any gear shift, produce variations in the attitude of the vehicle, which, albeit of brief duration, may at times impair driving comfort. Such variations are caused by the necessity to release the clutch of the robot-operated mechanical transmission before effecting any gear shift, thus resulting in a sudden fall in the drive torque transmitted to the wheels, and in an unstable attitude of the vehicle. Like conventional mechanical transmissions, in fact, to effect any gear shift, robot-operated mechanical transmissions of the above type require a zero, or near-zero, drive torque at the input of the main transmission shaft.
More specifically, when effecting any gear shift, robot-operated mechanical transmissions of the above type temporarily alter the attitude of the vehicle, producing a longitudinal oscillating or so-called xe2x80x9cpitchingxe2x80x9d movement which the driver finds particularly annoying, especially when the robot-operated mechanical transmission is operating in automatic. In automatic mode, in fact, gear shifting is controlled directly by the electronic central control unit of the transmission, so that the longitudinal oscillating movements of the vehicle occur one after another with no warning, i.e. without allowing the driver to prepare psychologically for the resulting variation in the attitude of the vehicle.
It is an object of the present invention to provide a vehicle attitude control device designed to improve the comfort of vehicles equipped with robot-operated mechanical transmissions by counteracting the onset of longitudinal oscillating movements when shifting gear.
According to the present invention, there is provided a vehicle attitude control device comprising a number of electronically controlled shock absorbers, and an electronic central control unit for driving said electronically controlled shock absorbers so as to regulate, instant by instant, the damping capacity of each; the attitude control device being characterized in that said electronic central control unit comprises control means for determining when a gear shift is about to be made; selecting means for determining a shock absorber regulation strategy best suited to counteract the onset of attitude variations produced by the pending gear shift; and shock absorber drive means for controlling the electronically controlled shock absorbers in such a manner as to implement the shock absorber regulation strategy selected by the selecting means.
The present invention also relates to a vehicle attitude control method.
According to the present invention, there is provided a method of controlling the attitude of a vehicle equipped with electronically controlled shock absorbers capable of varying damping capacity on command; the method being characterized by comprising the steps of determining the start of the gear shift procedure; selecting a shock absorber regulation strategy best suited to counteract the onset of attitude variations produced by the pending gear shift; and implementing said regulation strategy when shifting gear.